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Cladopyxidium
From Williams et al., 2017:
[Cladopyxidium, McLean, 1972, p. 862; Emendations: Stover and Evitt, 1978, p. 29-30; Below, 1987b, p. 32-33
tax. jr. syn. of Palaeostomocystis Deflandre, 1937, according to Marheinecke, 1992. Lentin and Williams, 1993, retained Cladopyxidium as a separate genus.
Type species: Cladopyxidium saeptum, McLean, 1972 (pl.1, figs.5–8)]
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Original description: [McLean, 1972]:
Diagnosis:
Cyst small, flask-like, with short apical neck-like rim, and nearly circular equatorial section. Cyst wall single-layered bearing septa which outline plate equivalents indicating tabulation of ?`, ?a, 7``, 6c+tr., 6```, 1p, 1````.
Archeopyle apical, circular with neck-like rim; corresponds to several apical plates; several anterior intercalary plate equivalents occur between the edge of the archeopyle and the precingular plate equivalents.
Cingulum approximately equatorial, weakly levorotatory.
Sulcus broad posteriorly; narrows towards cingulum.
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Emended descriptions:
Stover and Evitt 1978:
Synopsis:
Cysts proximate, subspherical to ellipsoidal; paratabulation indicated by parasutural ridges or septa, formula 4`, 3-4a, 6``, 6c, 6```, 1p, 1````, 5s; archeopyle apical, atypical; outline circular, or nearly so; operculum consists of paraplates 2` and 3`.
Description:
Shape: Subspherical to ellipsoidal; apical end commonly with short neck-like rim.
Wall relationships: Autophragm only.
Wall features: Parasutural ridges or septa smooth, as is the rest of the cyst. Paratabulation: Indicated by parasutural ridges or septa; formula: 4`, 3-4a, 6``, 6c, 6```, 1p, 1````, 5s.
Archeopyle: Apical, atypical; outline circular or nearly so; operculum normally free and consists of paraplates 2` and 3`.
Paracingulum: Indicated by six transversely elongate, rectangular paraplates.
Parasulcus: Clearly indicated; normally has four small paraplates at its apical end in vicinity of paracingulum, and a single large paraplate on the hypocyst.
Size: Small.
Remarks: our emendation of Cladipyxidium, based on numerous well- preserved specimens and on a reexamination of the type specimens, involves mainly a reinterpretation of the paratabulation, as a comparison of McLean`s (1972) paratabulation formula with ours indicates.
Affinities:
Cladopyxidium differs from Microdinium in having an atypically apical archeopyle with a more or less circular outline formed by the release of paraplates 2` and 3`. In Microdinium, apical archeopyle formation involves all of the apical paraplates, and if anterior intercalary paraplates are present, these too are released as a part of the operculum.
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Below, 1987: (Translation: Fensome et al., 1991, p. 134)
Diagnosis:
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 4`, 4a, 7``, 7c, 6```, 2````, as, FM subdivided into several periflagellar platelets, ls, rs, ps; pentagonal 1```` and hexagonal 2```` partiform, omegaform ps very large; adelopore on suture 1`/4`; growth of plates peridinoidal or ?gonyaulcoidal.
Cyst habit proximate, proximochorate, acavate, cavate, spheroidal, ovoidal, ovaloidal, polyhedral; size usually small; wall composed of pedium and firm, spongy, alo tegillate to tectate luxuria, surface glabrous or ornamented, nonareate or areate, areation marked by finate ornament, limbi, and intraareate ornament; areation formula NR PR/cop, pop, cap, NR`/4`, NRa/4a, NR``/7``, NRc/7c, Nr```/6```, NR````/2````, NRs/as, FM, ls, ps; 2 antapicals partiform; archaeopyle apical, PR+2`+3`; operculum foederate, secate, general opercular formula (PR+2`+3`).
Affinities:
In habit, total number of areas, and their distribution among respective series, Cladopyxidium resembles Phanerodinium. The only differences are in the location on and shape of individual area of the epicyst and their mutual arrangement. 1`` is triangular and does not extend to 2`, but is separated from 2` by 1` and 2``, which meet anterior to 1``. 4`` is located dorsally and finis 3``/4`` is DDL, 5`` shifts from R to DR, and 6`` is very extended transversely. All of these points indicate a counter-clockwise torsion of area 4``-6``. This removes the mirror symmetry of the precingulars on the dextral and sinistral sides of the dorsoventral plane as seen in Phanerodinium. 2` and 3` rotate counterclockwise. In Phanerodinium, they enclose PR exactly at L and R, finis 2`/3` lies in the dorsoventral plane, 2` borders 1``, 2``, 1a and 2a, and 3` borders 2a, 3a, 4a and 4`. In Cladopyxidium, finis 2`/3` swings to dextral, because 2` shifts to D. 2` thus loses its contact with 1``, but now also reaches to 3a. PR now adjoins 2` and 3` only ventrally. Correspondingly, the geniculate anterior finis, and the linear anterior finis of 3a in Phanerodinium becomes geniculate in Cladopyxidium. The centers of area 1a-4a, 1`, 3` and 4` remain essentially in the same place throughout these changes; however, 1a becomes abnormally elongate longitudinally as point 1a.2```.3`` moves far towards the cingulum.
On all specimens if this genus hitherto examined with a SEM, area rs is absent.
Reflected overlapping of thecal plates is established for Cladopyxidium velatum. The thecal plates grew only on he overlapping margins, in the gonyaulacoidal fashion.
Cladopyxidium and Phanerodinium differ conspicuously in their type of archaeopyle, viz. PR+2`+3` in Cladopyxidium and PR+1`+2`+3`+4`+ 1a+2a+3a+4a in Phanerodinium.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cladopyxidium McLean, 1972, as emended by Below (1987, p.32), has a tabulation of cop, pop, cap, 4`, 4a, 7`, 7c, 6"' , 2"'' (partiform), as, FM subdivided into several platelets, ls, rs, ps. 1"'' pentagonal, 2"'' hexagonal and partiform, ps omegaform and very large. Cyst small, surface smooth or ornamented. Archeopyle apical, PR + 2` + 3`, operculum foederate, secate.
[Cladopyxidium, McLean, 1972, p. 862; Emendations: Stover and Evitt, 1978, p. 29-30; Below, 1987b, p. 32-33
tax. jr. syn. of Palaeostomocystis Deflandre, 1937, according to Marheinecke, 1992. Lentin and Williams, 1993, retained Cladopyxidium as a separate genus.
Type species: Cladopyxidium saeptum, McLean, 1972 (pl.1, figs.5–8)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [McLean, 1972]:
Diagnosis:
Cyst small, flask-like, with short apical neck-like rim, and nearly circular equatorial section. Cyst wall single-layered bearing septa which outline plate equivalents indicating tabulation of ?`, ?a, 7``, 6c+tr., 6```, 1p, 1````.
Archeopyle apical, circular with neck-like rim; corresponds to several apical plates; several anterior intercalary plate equivalents occur between the edge of the archeopyle and the precingular plate equivalents.
Cingulum approximately equatorial, weakly levorotatory.
Sulcus broad posteriorly; narrows towards cingulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Stover and Evitt 1978:
Synopsis:
Cysts proximate, subspherical to ellipsoidal; paratabulation indicated by parasutural ridges or septa, formula 4`, 3-4a, 6``, 6c, 6```, 1p, 1````, 5s; archeopyle apical, atypical; outline circular, or nearly so; operculum consists of paraplates 2` and 3`.
Description:
Shape: Subspherical to ellipsoidal; apical end commonly with short neck-like rim.
Wall relationships: Autophragm only.
Wall features: Parasutural ridges or septa smooth, as is the rest of the cyst. Paratabulation: Indicated by parasutural ridges or septa; formula: 4`, 3-4a, 6``, 6c, 6```, 1p, 1````, 5s.
Archeopyle: Apical, atypical; outline circular or nearly so; operculum normally free and consists of paraplates 2` and 3`.
Paracingulum: Indicated by six transversely elongate, rectangular paraplates.
Parasulcus: Clearly indicated; normally has four small paraplates at its apical end in vicinity of paracingulum, and a single large paraplate on the hypocyst.
Size: Small.
Remarks: our emendation of Cladipyxidium, based on numerous well- preserved specimens and on a reexamination of the type specimens, involves mainly a reinterpretation of the paratabulation, as a comparison of McLean`s (1972) paratabulation formula with ours indicates.
Affinities:
Cladopyxidium differs from Microdinium in having an atypically apical archeopyle with a more or less circular outline formed by the release of paraplates 2` and 3`. In Microdinium, apical archeopyle formation involves all of the apical paraplates, and if anterior intercalary paraplates are present, these too are released as a part of the operculum.
------------------------------
Below, 1987: (Translation: Fensome et al., 1991, p. 134)
Diagnosis:
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 4`, 4a, 7``, 7c, 6```, 2````, as, FM subdivided into several periflagellar platelets, ls, rs, ps; pentagonal 1```` and hexagonal 2```` partiform, omegaform ps very large; adelopore on suture 1`/4`; growth of plates peridinoidal or ?gonyaulcoidal.
Cyst habit proximate, proximochorate, acavate, cavate, spheroidal, ovoidal, ovaloidal, polyhedral; size usually small; wall composed of pedium and firm, spongy, alo tegillate to tectate luxuria, surface glabrous or ornamented, nonareate or areate, areation marked by finate ornament, limbi, and intraareate ornament; areation formula NR PR/cop, pop, cap, NR`/4`, NRa/4a, NR``/7``, NRc/7c, Nr```/6```, NR````/2````, NRs/as, FM, ls, ps; 2 antapicals partiform; archaeopyle apical, PR+2`+3`; operculum foederate, secate, general opercular formula (PR+2`+3`).
Affinities:
In habit, total number of areas, and their distribution among respective series, Cladopyxidium resembles Phanerodinium. The only differences are in the location on and shape of individual area of the epicyst and their mutual arrangement. 1`` is triangular and does not extend to 2`, but is separated from 2` by 1` and 2``, which meet anterior to 1``. 4`` is located dorsally and finis 3``/4`` is DDL, 5`` shifts from R to DR, and 6`` is very extended transversely. All of these points indicate a counter-clockwise torsion of area 4``-6``. This removes the mirror symmetry of the precingulars on the dextral and sinistral sides of the dorsoventral plane as seen in Phanerodinium. 2` and 3` rotate counterclockwise. In Phanerodinium, they enclose PR exactly at L and R, finis 2`/3` lies in the dorsoventral plane, 2` borders 1``, 2``, 1a and 2a, and 3` borders 2a, 3a, 4a and 4`. In Cladopyxidium, finis 2`/3` swings to dextral, because 2` shifts to D. 2` thus loses its contact with 1``, but now also reaches to 3a. PR now adjoins 2` and 3` only ventrally. Correspondingly, the geniculate anterior finis, and the linear anterior finis of 3a in Phanerodinium becomes geniculate in Cladopyxidium. The centers of area 1a-4a, 1`, 3` and 4` remain essentially in the same place throughout these changes; however, 1a becomes abnormally elongate longitudinally as point 1a.2```.3`` moves far towards the cingulum.
On all specimens if this genus hitherto examined with a SEM, area rs is absent.
Reflected overlapping of thecal plates is established for Cladopyxidium velatum. The thecal plates grew only on he overlapping margins, in the gonyaulacoidal fashion.
Cladopyxidium and Phanerodinium differ conspicuously in their type of archaeopyle, viz. PR+2`+3` in Cladopyxidium and PR+1`+2`+3`+4`+ 1a+2a+3a+4a in Phanerodinium.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cladopyxidium McLean, 1972, as emended by Below (1987, p.32), has a tabulation of cop, pop, cap, 4`, 4a, 7`, 7c, 6"' , 2"'' (partiform), as, FM subdivided into several platelets, ls, rs, ps. 1"'' pentagonal, 2"'' hexagonal and partiform, ps omegaform and very large. Cyst small, surface smooth or ornamented. Archeopyle apical, PR + 2` + 3`, operculum foederate, secate.